Afishah Alias

Fabrication of ZnO Thin-Film Transistors by Chemical Vapor Deposition Method using Zinc Acetate Solution

Zinc oxide (ZnO) thin-film transistors (TFTs) were fabricated by thermal chemical vapor deposition (CVD) using aqueous solutions of zinc acetate (ZnAc2) dihydrate as a source. The precursor was supplied to the substrate by the nitrogen bubbling method through a plate with numerous orifices in the ZnAc2 solution. The ZnO thin films were grown on silicon substrates in the growth temperature (TG) range from 280 to 700 °C. The growth rate of ZnO thin films were linearly proportional to the growth temperature, which suggested that the growth rate is limited by the decomposition of ZnAc2. Depletion-mode TFTs with the ZnO film grown at TG = 350 °C was found to exhibit a relatively low saturation mobility (µsat). However, µsat increased from 1 to 14 cm2V-1s-1 and the operational mode was changed from the depletion mode to the enhancement mode by annealing treatment at 200 °C for 2 h under N2 ambient.

Temperature Dependence of CuGaO2 Films Fabricated by Sol–Gel Method

P-type CuGaO2 films have been fabricated on silicon substrates by the sol–gel method. The stable sol solutions for CuGaO2 growth were developed by the mixing of Cu–O and Ga–O sol solutions using copper(II) acetate monohydrate and tris(acetylacetonato) gallium(III), respectively. Phase separation in CuGaO2 films depends on the sol solution temperature and postbake temperature and duration. CuGaO2 films without a CuO phase were fabricated by postbaking at temperatures of approximately 800 °C for 1 h in N2 atmosphere. The sol–gel-derived CuGaO2 films show high transparency of more than 80% in the visible range, and the energy gap is approximately 3.6 eV.

Calculation of the Rate of Helium Ion Dispersion in Gallium Arsenide Compound

Nuclear dispersion is an important aspect in the process of slowing down ions by transferring their momentum to the target atoms and in determining path of the ion. This paper concerns the quantitative evaluation of the mechanism at which helium ions lose their energy when penetrate into a solid and the eventual distribution of the helium ion while stopping inside the Gallium Arsenide compound (GaAs). The first order effects of the atoms of the compound such as the electronic excitation of the atom, the lattice damage incurred to it, as well as the production of phonons in Gallium Arsenide due to the helium ions are also taken into account. The main finding is the mechanism of penetration of helium ions in GaAs, which is affected by the energy, the angle of incidence, and penetration density of the helium ions. It is found out that the energy has major impact than the angle of incidence in the interaction.

Conductance and Capacitance Responses of Metal-Organic-Metal Structure Based Organic Semiconductor Thin Film

In this work we have investigated the frequency and the bias voltage dependence of the electrical responses of organic structures based on poly (triarylamine) (PTAA) thin film using ITO/Organic/Al diode structure. The frequency-dependent and bias voltage-dependent conductance and capacitance were investigated using a precision LCR meter with wide frequency test (10 Hz – 100 kHz) and various bias voltages ranges (0.2 to 5.0 V), respectively. Investigation revealed that conductance was strongly dependent on the frequency and bias voltage-dependent. Conductance was inversely proportional to the capacitance among the frequency. Meanwhile, the capacitance and series resistance were dependent until a certain value at the low frequency region, but the capacitance and series resistance were independent at high frequencies.

Influence of substrate temperature and post annealing of CuGaO2 thin films on optical and structural properties

A transparent p-type thin film CuGaO2 was deposited by using RF sputtering deposition method on plastic (PET) and glass substrate. The characteristics of the film is investigated. The thin film was deposited at temperature range from 50-250°C and the pressure inside the chamber is 1.0×10−2 Torr and Argon gas was used as a working gas. The RF power is set to 100 W. The thickness of thin film is 300nm. In this experiment the transparency of the thin film is more than 70% for the visible light region. The band gap obtain is between 3.3 to 3.5 eV. The details of the results will be discussed in the conference.

Structural properties 3,16-bis triisopropylsilylethynyl (pentacene) (TIPS-pentacene) thin films onto organic dielectric layer using slide coating method

3,16-bis triisopropylsilylethynyl (Pentacene) (TIPS-Pentacene) compactable interface property is important in order to have a good arrangement of molecular structure. Comparison for TIPS-Pentacene deposited between two different surface layers conducted. 0.1wt% TIPS-Pentacene diluted in chloroform were deposited onto poly(methylmeaclyrate) (PMMA) layered transparent substrates using slide coating method. X-ray diffraction (XRD) used to determine crystallinity of thin films. Series of (00l) diffraction peaks obtained with sharp first peaks (001) for TIPS-Pentacene deposited onto PMMA layer at 5.35° and separation of 16.3 A. Morphology and surface roughness were carried out using scanning electron microscope (SEM) and surface profilemeter LS500, respectively.TIPS-Pentacene deposited onto PMMA layer formed needled-like-shape grains with 10.26 nm surface roughness. These properties were related as thin film formed and its surface roughness plays important role towards good mobility devices.

Temperature dependence of Ga:ZnO film deposited by RF magnetron sputtering

This paper investigate the dependence of substrate temperature onto characteristic of Gallium doped Zinc Oxide (Ga:ZnO). Ga:ZnO films were deposited on a glass substrate by RF Magnetron Sputtering using Ga:ZnO ceramic target with 99.99% purity. Sputtering power, argon flow and target distance were fixed in order to investigate the influence of substrate temperature to the growth characteristic, structural and optical properties of the films. Sputtering was performed with RF power of 100 Watt and the argon flow in was set at 10 sccm. The deposition times were fixed at 40 minute for all films. The result shows growth rate for Ga:ZnO growth at higher temperature are lower than at room temperature. Ga:ZnO thin films on different substrate temperature were successfully deposited onto glass substrate. All films are polycrystalline with (0 0 2) preferential orientation and fully transparent films with high transparency over 80 percent were achieved.

Electrical Characterization and Source-Drain Voltage Dependent Mobility of P-Channel Organic Field-Effect Transistors Using MATLAB Simulation

We demonstrate fabrication of bottom gate/top source-drain contacts for p-channel (small molecule) organic field-effect transistor (OFET) using pentacene as an active semiconductor layer and silicon dioxide (SiO2) as gate dielectric. The device exhibits a typical output curve of a field-effect transistor (FET). Furthermore, analysis of electrical characterization was done to investigate the source-drain voltage (Vds) dependent mobility. The mobility which calculated using MATLAB simulation exhibited a range from 0.0234 to 0.0258 cm2/Vs with increasing source-drain voltage (average mobility was 0.0254 cm2/Vs). This work suggests that the mobility increase with increasing source-drain voltage similar to the gate voltage dependent mobility phenomenon.

Effect of [6,6]-Phenyl-C 61 butyric acid methyl ester (PCBM) agglomerated nanostructure on device performance in organic thin-film transistors

The influence of [6,6]-phenyl C₆₁-butyric acid methyl ester (PCBM) agglomerated nanostructure on device performance of pentacene-based organic thin-film transistors (OTFTs) were reported. The presence of PCBM layers on a SiO₂ gate dielectric resulted in a good electrical characteristics of pentacene-based OTFTs, including a relatively high mobility (μ = 0.95-2.2 cm² V^-1 s^-1), low threshold voltages (V_th = -1.1 - -5.4 V), a high on/off current ratio (I_on/I_off = 10⁴), and a high value of subthreshold slope (SS = 6.5 V/decade). The surface topography studies reveal that the PCBM nanostructure could favor the reduction of grain boundaries, which resulted in a better transistor performance of pentacene-based OTFTs. The influence of PCBM on the molecular microstructure of pentacene thin films elucidates a reasonable explanation for higher performance on OTFTs.

Electrical and structural characterization of Zn doped CuGaO 2 films

Oxide materials have been widely used in opto-electro devices due to their wide bandgap energy, high optical transparency in the visible light region, and wide range resistance. Recently, delafossite CuMO2 (M=Al, Ga, In) have been widely studied for p-type oxide semiconductors. In this study, CuGaO2 was chosen due to its smaller lattice mismatch with ZnO compared with CuAlO2 for the possibility of p-n junction device in the future work. Zn as impurity atoms was introduced to fabricate quaternary CuZnGaO2 films to reduce lattice mismatch with ZnO. In order to study the effect of the substitute site of the Zn ion for generating donor or acceptor, 3 methods of preparation of the Cu-Zn-Ga-O sol solution were also demonstrated. In this paper, the electrical and structural properties of Zn doped on the sol-gel derived CuGaO2 films have been investigated. The diffraction angle of the CuGaO2 films are shifted to lower angle with increasing Zn%, indicating the lattice expansion which proved that the introducing Zn as impurity atoms was able to reduce lattice mismatch between CuGaO2 and ZnO. While the curve in the negative gate bias Vg proved the hole dominated transport properties. The curve in the positive gate bias can be suppressed by introducing Zn.